I haven't seen this Blake yet, but I loaded my other game to check and I think I figured it out. In the game where I talked to Homer first I got the kill the trolls quest. In the game where I talked to Trisha first I did not get the kill the trolls quests. In neither game did I talk to anyone named Blake, so he can't be the trigger. Both games are the same otherwise from what I can tell. I cannot seem to fix this now, so I guess I continue without the quest.
